A closer look at the ZFS file system

SUN's ZFS file system became part of FreeBSD on 6th
April 2007. ZFS is a new kind of file system that
provides simple administration, transactional
semantics, end-to-end data integrity, and immense
scalability. ZFS is not an incremental improvement
to existing technology; it is a fundamentally new
approach to data management. We've blown away 20
years of obsolete assumptions, eliminated complexity
at the source, and created a storage system that's
actually a pleasure to use.

ZFS presents a pooled storage model that completely
eliminates the concept of volumes and the associated
problems of partitions, provisioning, wasted bandwidth
and stranded storage. Thousands of file systems can
draw from a common storage pool, each one consuming
only as much space as it actually needs. The combined
I/O bandwidth of all devices in the pool is available
to all filesystems at all times.

All operations are copy-on-write transactions, so
the on-disk state is always valid. There is no need
to fsck(1M) a ZFS file system, ever. Every block
is checksummed to prevent silent data corruption,
and the data is self-healing in replicated (mirrored
or RAID) configurations. If one copy is damaged,
ZFS detects it and uses another copy to repair it.